We will conduct a pharmacogenetic study to assess, in a population of metastatic breast cancer (MBC) patients, the possible predictive role of VEGF-A, VEGF receptor-2 (VEGFR-2), interleukin-8 (IL-8), hypoxia inducible factor-1α (HIF-1α), hypoxia inducible factor-2α (HIF-2α) and thrombospondin-1 (TSP-1) SNPs for bevacizumab response when combined with first-line paclitaxel and for progression free survival (PFS). Analyses will be performed on germline DNA obtained from blood samples and SNPs will be investigated by real-time polymerase chain reaction (PCR) technique. The multifactor dimensionality reduction (MDR) methodology will be applied to investigate the interaction between SNPs.